must substitute
Regular verb: substitute - substituted- substituted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must substitute
you must substitute
she must substitute
we must substitute
you must substitute
they must substitute 	I must be substituting
you must be substituting
she must be substituting
we must be substituting
you must be substituting
they must be substituting	I must have substituted
you must have substituted
she must have substituted
we must have substituted
you must have substituted
they must have substituted	I must have been substituting
you must have been substituting
she must have been substituting
we must have been substituting
you must have been substituting
they must have been substituting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't substitute
you mustn't substitute
she mustn't substitute
we mustn't substitute
you mustn't substitute
they mustn't substitute 	I mustn't be substituting
you mustn't be substituting
she mustn't be substituting
we mustn't be substituting
you mustn't be substituting
they mustn't be substituting	I mustn't have substituted
you mustn't have substituted
she mustn't have substituted
we mustn't have substituted
you mustn't have substituted
they mustn't have substituted	I mustn't have been substituting
you mustn't have been substituting
she mustn't have been substituting
we mustn't have been substituting
you mustn't have been substituting
they mustn't have been substituting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I substitute?
must you substitute?
must she substitute?
must we substitute?
must you substitute?
must they substitute? 	must I be substituting?
must you be substituting?
must she be substituting?
must we be substituting?
must you be substituting?
must they be substituting? 	must I have substituted?
must you have substituted?
must she have substituted?
must we have substituted?
must you have substituted?
must they have substituted? 	must I have been substituting?
must you have been substituting?
must she have been substituting?
must we have been substituting?
must you have been substituting?
must they have been substituting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I substitute?
mustn't you substitute?
mustn't she substitute?
mustn't we substitute?
mustn't you substitute?
mustn't they substitute? 	mustn't I be substituting?
mustn't you be substituting?
mustn't she be substituting?
mustn't we be substituting?
mustn't you be substituting?
mustn't they be substituting? 	mustn't I have substituted?
mustn't you have substituted?
mustn't she have substituted?
mustn't we have substituted?
mustn't you have substituted?
mustn't they have substituted? 	mustn't I have been substituting?
mustn't you have been substituting?
mustn't she have been substituting?
mustn't we have been substituting?
mustn't you have been substituting?
mustn't they have been substituting?